Impact of β(S)-globin haplotypes on oxidative stress in patients with sickle cell anemia in steady state

In Brazil, sickle cell anemia (SCA) is one of the most common genetic disorders. The levels of fetal hemoglobin (HbF) may be influenced by the presence of genetic modifiers; among these are the β(S)-globin haplotypes, associated with the clinical heterogeneity presented by the disease. Patients with SCA have an imbalance between the production of reactive oxygen species and antioxidant capacity, generating oxidative stress. Nitric oxide (NO) is a potent vasodilator and may be involved in the mechanism of HbF induction. The aim of this study was to evaluate the impact of β(S)-globin haplotypes in oxidative stress in patients with SCA.

The study included 47 patients with SCA in steady state. The molecular diagnosis of SCA and characterization of the β(S)-globin haplotype was performed by β(S) chain polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Concentration of HbF was determined by high-performance liquid chromatography (HPLC). Serum levels of nitrite/nitrate (NOx) and malondialdehyde were determined by spectrophotometry.

The most prevalent haplotype in the study population was Bantu. The Benin/n group presented significantly higher HbF and nitrite levels as compared to the Bantu/n group.

Our results confirm data reported in the literature where the Benin and Bantu haplotypes are respectively correlated to high levels and decreased HbF. In addition, haplotypes associated with high levels of HbF showed high levels of nitrite, demonstrating that as the HbF, serum levels of NOx may prove useful as a prognostic biomarker in patients with SCA.